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That such a factorization is possible is well-known to algebraists (and expressed by the formulaSL(n;R[z, z-1])=E(n;R[z, z-1])); it is also used in linear systems theory in the electrical engineering community.
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Following the methodology of community ecology, the total root mass of a phytocommunity is measured as cubic volume.
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The RENIs of three community types (Picea crassifolia + Hippophae rhamnoides ssp.
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The standing crop of N in the plant community was 1,025.28 kg/hm2, accumulation in the litter layer was 224.88 kg/hm2, and reserve in the soil was 55,151 kg/hm2.
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Compared with other forest types, cycling rate of N in the community was lower than in deciduous broad-leaved forests, rain forests, and mangroves, and was moderate in evergreen broad-leaved forests.
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| During the rice growing seasons in 1961, the authors conducted a series of ob-servations on the rice insect pests around the Dung-ting Lake of Hunan province. Atotal of 46 species of rice pests was found, the 45 insect species belonging to 18 dif-ferent families and 8 orders, the other pest belonging to order Oligochaeta. Amongthese pests, the rice stem borers (3 spp.), the leafhoppers (4 spp.), the grasshoppers(2 spp.), the rice leaf-rollers (2 spp.), the rice weevil (1 sp.), the leaf beetle (1 sp.),the thrips... During the rice growing seasons in 1961, the authors conducted a series of ob-servations on the rice insect pests around the Dung-ting Lake of Hunan province. Atotal of 46 species of rice pests was found, the 45 insect species belonging to 18 dif-ferent families and 8 orders, the other pest belonging to order Oligochaeta. Amongthese pests, the rice stem borers (3 spp.), the leafhoppers (4 spp.), the grasshoppers(2 spp.), the rice leaf-rollers (2 spp.), the rice weevil (1 sp.), the leaf beetle (1 sp.),the thrips (2 spp.), and the Annelida (1 sp.), are considered as major pests of rice in thislocality. This paper not only deals with a comparison of the pest populations and com-munities between rice fields, planted to early rice, middle rice and late rice, but alsodeals with a similar comparison between the older and newer rice fields. The resultsmay be briefly summarized as follows: 1. In all the rice fields, the period of numerical summit of each insect populationdoes not appears at same time. 2. In all the rice fields, the important components of each insect community weredifferent. 3. In the older or newer rice fields, the communities and populations of rice insectpests were different. 4. Due to different history of the rice fields, different biological characters of theinsect pest, and different environment (climatic or dietary factors), the communities andpopulations of rice insect pests were also different. The causes of their difference weredescribed. | 本文记述了1961年在湖南滨湖区水稻生长季节中每五日调查稻虫的结果。 查明该地区共有水稻害虫46种。田间虫口密度大小因稻田类型和季节的不同而异,早稻田和中稻田有7种害虫数量较大,一季晚稻田有9种,双季晚稻田有4种。 全年内各种主要稻虫种群数量高峰出现的时间、次数、以及峰态的高低均有不同。种群数量较大的害虫,依其高峰期出现的迟早顺序,有稻象虫、稻蝗、二化螟、褐稻虱、黑尾叶蝉、稻苞虫、三化螟和粉白飞虱等。 在不同历史条件的稻田里,稻虫群体组成及数量互有差异。老稻田稻虫种类较复杂,主要稻虫虫口密度较高。新开稻田稻虫种类较少(如颤蚓、三化螟等),而叶蝉和飞虱等较多。 分析了稻田历史条件、稻由生物学特性、还及气候和食料条件,对于稻虫群体组成及种群数量变动的影响。 | This paper deals with the succession of insect community of citrts | 本文应用主分量分析方法探讨了昆虫群落随树龄的演替规律,并把随树龄的演替划分为三个阶段。总的趋势是:害虫优势种从喜食嫩叶的种类如黑刺粉虱、卷叶蛾等向在老树上为害重的类群如矢光蚧、天牛等转化;物种数由少变多,多样性和均匀度在第一阶段较低,第二阶段最高,第三阶段又下降。主分量分析还表明了引起桔园昆虫群落演替的主要昆虫类群及它们的变动规律。也比较了管理措施对桔园昆虫群落的影响,物种数以天然防治园最多,综防园次之,化防园最少;多样性、均匀度以综防园最大,其次是化防园,天然防治园最小,但群落内昆虫个体总数正好相反,天然防治园最多,其次是化防园,综防园最少。 | Community dissimilarity index (D_(ij)) in time series has been recommendedto indicate the stability of community. On the basis of succession of com-munity from pinus massoniana Lamb. -Dendrolimus punctatus Walker to P.massoniana-Hemiberlesia pitysophila Takagi in the Zaizhang Mountain, aforecasting model of succession trend of community has been developed byemploying grey system theory and combining GM(1, 1) model with identi-tying residual error. It indicates that when H. pitysophila intrudes intopine... Community dissimilarity index (D_(ij)) in time series has been recommendedto indicate the stability of community. On the basis of succession of com-munity from pinus massoniana Lamb. -Dendrolimus punctatus Walker to P.massoniana-Hemiberlesia pitysophila Takagi in the Zaizhang Mountain, aforecasting model of succession trend of community has been developed byemploying grey system theory and combining GM(1, 1) model with identi-tying residual error. It indicates that when H. pitysophila intrudes intopine forest, the insect community on the plots of the first category will keepstable after fluctuating for a period of time; while the insect community onthe plots of the second category will collapse after five years. In order to identifing the cause of the findings, the GM(1, 5) model ofD_(ij) to the community diversity indexes e~(H'), e~(H'_h), e~(H'_(pred)), e~(H'_(para)) hasbeen constructed. The results indicate that it is the enemy control system andcompensation capacity or pine forest that cause tbe community stable. | 本文提出以同一群落不同时间序列上的D_(ij)值作为群落稳定性测度。在寨场山马尾松——马尾松毛虫群落向马尾松——松针突圆蚧群落演替的基础上,运用灰色系统理论,对群落的演替趋势(D_(ij))建立了GM(1,1)与残差辨识相结合的预测模型。预测结果表明,当松针突圆蚧侵入林地后,第Ⅰ组样地上的昆虫群落经一段时间的波动后,将稳定下来;而第Ⅱ组样地上的昆虫群落,将在五年后崩溃瓦解。此外,还利用D_(ij)对于e~(H′),e~(H′h),e~(H′_(pred))和e~(H′_(para))建立了GM(1,5)模型,对形成上述演替趋势的原因进行了分析。结果表明:松林较好的营养条件和松针突圆蚧强的天敌控制系统,是使得第Ⅰ组样地中的昆虫群落稳定下来的条件,而第Ⅱ组样地中昆虫群落的崩溃瓦解,是马尾松林的毁灭所致。 | | | | << 更多相关文摘 |
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